采用晶体相场方法研究韧性单晶材料在双轴拉伸条件下微裂纹扩展与分叉的演化过程,分析应变、温度、初始裂口形状等因素对裂纹扩展和分叉的影响.结果表明:对于简单的单向拉伸,应变需要达到一定的临界值,裂纹扩展才会启动.对于二组相互垂直的双轴拉伸作用,当应变达到临界值后,裂纹扩展过程中会发生分叉现象.温度越高,裂纹扩展越快且分叉越多.裂纹在扩展过程中,体系能量不断降低,当裂纹出现分叉时,体系能量降低得更快.在裂纹扩展过程中,有时是会在裂尖处前方出现微小的空洞,类似在裂纹尖端前方出现位错发射情况,这些微小的空洞逐渐扩大连成裂纹.本文所得结果与相关模拟结果和实验结果符合.
Morphology of microcrack propagation and crack branching of single crystal ductile materials under tensile are simulated with phase-field-crystal method. It shows that shape of notch has a strong effect on crack propagation. With uniaxial tension crack propagation appears if only strain reaches a critical value. With biaxial tension a crack branches if only strain reaches a critical value.Temperature parameter takes significant effects on crack propagation. The smaller the temperature parameter is( the temperature is higher),the faster the cracks propagate and the more the crack branches are. It is observed that free energy of system decreases with time and decreases faster after crack starts to branch. During crack propagation,disconnectedly isolated cavities around the main cracks can be found and these defects become new cracks. They grow up along a line and become a branching crack. Simulated results are in agreement with other simulations and experimental results.